Rose Photo Album Advanced GIMP Users :: Isolating One Colour In A Black/white Photo...?

Advanced GIMP users :: Isolating one colour in a black/white photo...? - rose photo album

Well, we all know the pictures, most of them to hell, like emo, but I've always wanted to know how these people have to do. Here is an example of what I'm talking about: http://i201.photobucket.com/albums/aa291 ...

How can I make a photo and remove all colors up to a specific region? Is there an easy way to do this?